Oracle Database 12c SQL Fundamentals I Exam Guide Exam 1Z0-061 学习笔记
I.anyarithmaticoperatorwithnullwillresultnullconcatenullwillnotresultinnull,willremainthesamewithoutnullII,for'inliteralvalue,coulduse''toescapetheit.orcoulduseq''touseescapethe'intheliteralvalue,here